Steam treatment stations for chemical mechanical polishing system

ABSTRACT

An apparatus for steam treatment of a carrier head or a substrate in a chemical mechanical polishing system includes a load cup, a pedestal in a cavity defined by the load cup, the pedestal configured to receive a substrate from or supply a substrate to a carrier head, a boiler to generate steam, one or more nozzles positioned to direct steam inwardly into the cavity defined by the load cup, and a supply line running from the boiler to the one or more nozzles to supply steam to the one or more nozzles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 62/854,305, filed on May 29, 2019, the entire disclosure of which isincorporated by reference.

TECHNICAL FIELD

The present disclosure relates to chemical mechanical polishing (CMP),and more specifically to the use of steam for cleaning or preheatingduring CMP.

BACKGROUND

An integrated circuit is typically formed on a substrate by thesequential deposition of conductive, semiconductive, or insulativelayers on a semiconductor wafer. A variety of fabrication processesrequire planarization of a layer on the substrate. For example, onefabrication step involves depositing a filler layer over a non-planarsurface and planarizing the filler layer. For certain applications, thefiller layer is planarized until the top surface of a patterned layer isexposed. For example, a metal layer can be deposited on a patternedinsulative layer to fill the trenches and holes in the insulative layer.After planarization, the remaining portions of the metal in the trenchesand holes of the patterned layer form vias, plugs, and lines to provideconductive paths between thin film circuits on the substrate. As anotherexample, a dielectric layer can be deposited over a patterned conductivelayer, and then planarized to enable subsequent photolithographic steps.

Chemical mechanical polishing (CMP) is one accepted method ofplanarization. This planarization method typically requires that thesubstrate be mounted on a carrier head. The exposed surface of thesubstrate is typically placed against a rotating polishing pad. Thecarrier head provides a controllable load on the substrate to push itagainst the polishing pad. A polishing slurry with abrasive particles istypically supplied to the surface of the polishing pad.

SUMMARY

In one aspect, an apparatus for steam treatment of a carrier head or asubstrate in a chemical mechanical polishing system includes a load cup,a pedestal in a cavity defined by the load cup, the pedestal configuredto receive a substrate from or supply a substrate to a carrier head, aboiler to generate steam, one or more nozzles positioned to direct steaminwardly into the cavity defined by the load cup, and a supply linerunning from the boiler to the one or more nozzles to supply steam tothe one or more nozzles.

Implementations can include one or more of the following features.

A motor can rotate the carrier head when the carrier head is within theload cup.

An actuator can lift or lower the carrier head within the load cup.

A temperature sensor can monitor a temperature of the carrier headand/or substrate. A controller can be configured to receive thetemperature from the sensor and to halt a flow of steam when the carrierhead or substrate reaches a target temperature.

A controller can be configured to start a timer when the steam begins toflow onto the carrier head or substrate and to halt the flow of steamwhen the timer expires.

The one or more nozzles can include a first nozzle, and can furtherinclude a controller configured to cause steam to flow through the firstnozzle onto an outer surface of the carrier head when the carrier headis positioned in the load cup.

The one or more nozzles can include a second nozzle, and can furtherinclude a controller configured to cause steam to flow through thesecond nozzle onto an interior surface of the carrier head when thesubstrate is positioned on the pedestal.

The controller can be configured to cause steam to flow through thesecond nozzle onto a bottom surface of the substrate when the substrateis loaded in the carrier head.

The one or more nozzles can include a third nozzle and a fourth nozzle,and can further include a controller configured to cause steam to flowthrough the third nozzle onto a top surface of the substrate when thesubstrate is positioned on the pedestal. The one or more nozzles caninclude a fourth nozzle, and the controller can be configured to causesteam to flow through the fourth nozzle onto a bottom surface of thesubstrate when the substrate is positioned on the pedestal.

In one aspect, a method of steam treatment of a carrier head or asubstrate in a chemical mechanical polishing system includes receiving acarrier head or/or substrate in a substrate loading cup of the achemical mechanical polishing system, and directing steam onto thecarrier head and/or substrate in the loading cup to clean and/or preheatthe carrier head and/or substrate.

In one aspect, an apparatus for steam treatment of a conditioner headand/or conditioner disk in a chemical mechanical polishing systemincludes a conditioner cleaning cup, a boiler to generate steam, one ormore nozzles positioned to direct steam inwardly into a cavity definedby the load cup, and a supply line running from the boiler to the one ormore nozzles to supply steam to the one or more nozzles.

Implementations can include one or more of the following features.

A temperature sensor can monitor a temperature of the conditioner headand/or conditioner disk. A controller can be configured to receive thetemperature from the sensor and to halt a flow of steam to theconditioner head or conditioner disk when the conditioner head orconditioner disk reaches a target temperature.

A controller can be configured to start a timer when the steam begins toflow onto conditioner head or conditioner disk and to halt the flow ofsteam when the timer expires.

The one or more nozzles can include a first nozzle, and can furtherinclude a controller configured to cause steam to flow through the firstnozzle onto a bottom surface of the conditioner disk when theconditioner head is positioned in the cleaning cup.

The one or more nozzles can include a second nozzle, and can furtherinclude a controller configured to cause steam to flow through thesecond nozzle onto an outer surface of the conditioner head when theconditioner head is positioned in the cleaning cup.

In one aspect, a method of steam treatment of a conditioner head and/orconditioner disk in a chemical mechanical polishing system includes:receiving a conditioner head in a conditioner cleaning cup of the achemical mechanical polishing system, and directing steam onto theconditioner head and/or conditioner head in the cleaning cup to cleanand/or preheat the conditioner head and/or conditioner disk.

Possible advantages may include, but are not limited to, one or more ofthe following.

Steam, i.e., gaseous H₂O generated by boiling, can be generated insufficient quantities with low levels of contaminants. Additionally, asteam generator can generate steam that is substantially pure gas, e.g.,has little to no suspended liquid in the steam. Such steam, also knownas dry steam, can provide a gaseous form of H₂O that has a higher energytransfer and lower liquid content than other steam alternatives such asflash steam.

Various components of a CMP apparatus can be quickly and efficientlycleaned. Steam can be more effective than liquid water in dissolving orotherwise removing polishing by-products, dried slurry, debris, etc.,from surfaces in the polishing system. Thus, defects on the substratecan be reduced.

Various components of a CMP apparatus can be pre-heated. Temperaturevariation across the polishing pad and thus across the substrate can bereduced, thereby reducing within-wafer non-uniformity (WIWNU).Temperature variation over a polishing operation can be reduced. Thiscan improve predictability of polishing during the CMP process.Temperature variations from one polishing operation to another polishingoperation can be reduced. This can improve wafer-to-wafer uniformity.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other aspects,features, and advantages will be apparent from the description anddrawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of an example of a polishing apparatus.

FIG. 2A is a schematic cross-sectional view of an example carrier headsteam treating assembly.

FIG. 2B is a schematic cross-sectional view of an example conditioninghead steam treating assembly.

FIG. 3A is a schematic cross-sectional view of an example of a polishingstation of the polishing apparatus.

FIG. 3B is a schematic top view of an example polishing station of thechemical mechanical polishing apparatus.

DETAILED DESCRIPTION

Chemical mechanical polishing operates by a combination of mechanicalabrasion and chemical etching at the interface between the substrate,polishing liquid, and polishing pad. During the polishing process, asignificant amount of heat is generated due to friction between thesurface of the substrate and the polishing pad. In addition, someprocesses also include an in-situ pad conditioning step in which aconditioning disk, e.g., a disk coated with abrasive diamond particles,is pressed against the rotating polishing pad to condition and texturethe polishing pad surface. The abrasion of the conditioning process canalso generate heat. For example, in a typical one minute copper CMPprocess with a nominal downforce pressure of 2 psi and removal rate of8000 Å/min, the surface temperature of a polyurethane polishing pad canrise by about 30° C.

On the other hand, if the polishing pad has been heated by previouspolishing operations, when a new substrate is initially lowered intocontact with the polishing pad, it is at a lower temperature, and thuscan act as a heat sink. Similarly, slurry dispensed onto the polishingpad can act as a heat sink. Overall, these effects result in variationof the temperature of the polishing pad spatially and over time.

Both the chemical-related variables in a CMP process, e.g., as theinitiation and rates of the participating reactions, and themechanical-related variables, e.g., the surface friction coefficient andviscoelasticity of the polishing pad, are strongly temperaturedependent. Consequently, variation in the surface temperature of thepolishing pad can result in changes in removal rate, polishinguniformity, erosion, dishing, and residue. By more tightly controllingthe temperature of the surface of the polishing pad during polishing,variation in temperature can be reduced, and polishing performance,e.g., as measured by within-wafer non-uniformity or wafer-to-wafernon-uniformity, can be improved.

Furthermore, debris and slurry can accumulate on various components ofthe CMP apparatus during CMP. If these polishing by-products later comeloose from the components, they can scratch or otherwise damage thesubstrate, resulting in an increase in polishing defects. Water jetshave been used to clean various components of the CMP apparatus system.However, a large quantity of water is needed to perform this task.

A technique that could address one or more of these issues is to cleanand/or pre-heat various components of the CMP apparatus using steam,i.e., gaseous H₂O generated by boiling. Less steam may be required toimpart an equivalent amount of energy as hot water, e.g., due to thelatent heat of the steam. Additionally, steam can be sprayed at highvelocities to clean and/or preheat the components. In addition, steamcan be more effective than liquid water in dissolving or otherwiseremoving polishing by-products.

FIG. 1 is a plan view of a chemical mechanical polishing apparatus 2 forprocessing one or more substrates. The polishing apparatus 2 includes apolishing platform 4 that at least partially supports and houses aplurality of polishing stations 20. For example, the polishing apparatuscan include four polishing stations 20 a, 20 b, 20 c and 20 d. Eachpolishing station 20 is adapted to polish a substrate that is retainedin a carrier head 70. Not all components of each station are illustratedin FIG. 1.

The polishing apparatus 2 also includes a multiplicity of carrier heads70, each of which is configured to carry a substrate. The polishingapparatus 2 also includes a transfer station 6 for loading and unloadingsubstrates from the carrier heads. The transfer station 6 can include aplurality of load cups 8, e.g., two load cups 8 a, 8 b, adapted tofacilitate transfer of a substrate between the carrier heads 70 and afactory interface (not shown) or other device (not shown) by a transferrobot 9. The load cups 8 generally facilitate transfer between the robot9 and each of the carrier heads 70 by loading and unloading the carrierheads 70.

The stations of the polishing apparatus 2, including the transferstation 6 and the polishing stations 20, can be positioned atsubstantially equal angular intervals around the center of the platform4. This is not required, but can provide the polishing apparatus with agood footprint.

For a polishing operation, one carrier head 70 is positioned at eachpolishing station. Two additional carrier heads can be positioned in theloading and unloading station 6 to exchange polished substrates forunpolished substrates while the other substrates are being polished atthe polishing stations 20.

The carrier heads 70 are held by a support structure that can cause eachcarrier head to move along a path that passes, in order, the firstpolishing station 20 a, the second polishing station 20 b, the thirdpolishing station 20 c, and the fourth polishing station 20 d. Thispermits each carrier head to be selectively positioned over thepolishing stations 20 and the load cups 8.

In some implementations, each carrier head 70 is coupled to a carriage78 that is mounted to a support structure 72. By moving a carriage 78along the support structure 72, e.g., a track, the carrier head 70 canbe positioned over a selected polishing station 20 or load cup 8.Alternatively, the carrier heads 70 can be suspended from a carousel,and rotation of the carousel moves all of the carrier headssimultaneously along a circular path.

Each polishing station 20 of the polishing apparatus 2 can include aport, e.g., at the end of a slurry supply arm 39, to dispense polishingliquid 38 (see FIG. 3A), such as abrasive slurry, onto the polishing pad30. Each polishing station 20 of the polishing apparatus 2 can alsoinclude pad conditioner 93 to abrade the polishing pad 30 to maintainthe polishing pad 30 in a consistent abrasive state.

FIGS. 3A and 3B illustrate an example of a polishing station 20 of achemical mechanical polishing system. The polishing station 20 includesa rotatable disk-shaped platen 24 on which a polishing pad 30 issituated. The platen 24 is operable to rotate (see arrow A in FIG. 3B)about an axis 25. For example, a motor 22 can turn a drive shaft 28 torotate the platen 24. The polishing pad 30 can be a two-layer polishingpad with an outer polishing layer 34 and a softer backing layer 32.

Referring to FIGS. 1, 3A and 3B, the polishing station 20 can include asupply port, e.g., at the end of a slurry supply arm 39, to dispense apolishing liquid 38, such as an abrasive slurry, onto the polishing pad30.

The polishing station 20 can include a pad conditioner 90 with aconditioner disk 92 (see FIG. 2B) to maintain the surface roughness ofthe polishing pad 30. The conditioner disk 92 can be positioned in aconditioner head 93 at the end of an arm 94. The arm 94 and conditionerhead 93 are supported by a base 96. The arm 94 can swing so as to sweepthe conditioner head 93 and conditioner disk 92 laterally across thepolishing pad 30. A cleaning cup 255 can be located adjacent the platen24 at a position to which the arm 94 can move the conditioner head 93.

A carrier head 70 is operable to hold a substrate 10 against thepolishing pad 30. The carrier head 70 is suspended from a supportstructure 72, e.g., a carousel or a track, and is connected by a driveshaft 74 to a carrier head rotation motor 76 so that the carrier headcan rotate about an axis 71. Optionally, the carrier head 70 canoscillate laterally, e.g., on sliders on the carousel, by movement alongthe track, or by rotational oscillation of the carousel itself.

The carrier head 70 can include a flexible membrane 80 having asubstrate mounting surface to contact the back side of the substrate 10,and a plurality of pressurizable chambers 82 to apply differentpressures to different zones, e.g., different radial zones, on thesubstrate 10. The carrier head 70 can include a retaining ring 84 tohold the substrate. In some implementations, the retaining ring 84 mayinclude a lower plastic portion 86 that contacts the polishing pad, andan upper portion 88 of a harder material, e.g., a metal.

In operation, the platen is rotated about its central axis 25, and thecarrier head is rotated about its central axis 71 (see arrow B in FIG.3B) and translated laterally (see arrow C in FIG. 3B) across the topsurface of the polishing pad 30.

Referring to FIGS. 3A and 3B, as the carrier head 70 sweeps across thepolishing pad 30, any exposed surfaces of the carrier head 70 tend tobecome covered with slurry. For example, slurry can stick to the outeror inner diameter surface of the retaining ring 84. In general, for anysurfaces that are not maintained in a wet condition, the slurry willtend to coagulate and/or dry out. As a result, particulates can form onthe carrier head 70. If these particulates become dislodged, theparticulates can scratch the substrate, resulting in polishing defects.

Moreover, the slurry can cake onto the carrier head 70, or the sodiumhydroxide in the slurry can crystallize on one of the surfaces of thecarrier head 70 and/or the substrate 10 and cause the surface of thecarrier head 70 to be corrode. The caked-on slurry is difficult toremove and the crystallized sodium hydroxide is difficult to return to asolution.

Similar problems occur with the conditioner head 92, e.g., particulatescan form on the conditioner head 92, the slurry can cake onto theconditioner head 92, or the sodium hydroxide in the slurry cancrystallize on one of the surfaces of the conditioner head 92. Onesolution is to clean the components, e.g., the carrier head 70 andconditioner head 92, with a liquid water jet. However, the componentscan be difficult to clean with a water jet alone, and a substantialamount of water may be necessary. Additionally, the components thatcontact the polishing pad 30, e.g., the carrier head 70, substrate 10and conditioner disk 92, can act as heat sinks that hinder uniformity ofthe polishing pad temperature.

To address these problems, as shown in the FIG. 2A, the polishingapparatus 2 includes one or more carrier head steam treating assemblies200. Each steam treating assembly 200 can be used for cleaning and/orpre-heating of the carrier head 70 and substrate 10.

A steam treating assembly 200 can be part of the load cup 8, e.g., partof the load cup 8 a or 8 b. Alternatively or in addition, a steamtreating assembly 200 can be provided at one or more inter-platenstations 9 located between adjacent polishing stations 20.

The load cup 8 includes a pedestal 204 to hold the substrate 10 during aloading/unloading process. The load cup 8 also includes a housing 206that surrounds or substantially surrounds the pedestal 204. Multiplenozzles 225 are supported by the housing 206 or a separate support todeliver steam 245 to a carrier head and/or substrate positioned in acavity 208 defined by the housing 206. For example, nozzles 225 can bepositioned on one or more interior surfaces of the housing 206, e.g., afloor 206 a and/or a side wall 206 b and/or a ceiling of the cavity. Thenozzles 225 can be oriented to direct steam inwardly into the cavity206. The steam 245 can be generated by using the steam generator 410,e.g., a boiler such as a flash boiler or a regular boiler. A drain 235can permit excess water, cleaning solution, and cleaning by-product topass through to prevent accumulation in the load cup 8.

An actuator provides relative vertical motion between the housing 206and the carrier head 70. For example, a shaft 210 can support thehousing 206 and be vertically actuatable to raise and lower the housing206. Alternatively, the carrier head 70 can move vertically. Thepedestal 205 can be on-axis with the shaft 210. The pedestal 204 can bevertically movable relative to the housing 206.

In operation, the carrier head 70 can be positioned over the load cup 8,and the housing 206 can be raised (or the carrier head 70 lowered) sothat the carrier head 70 is partially within the cavity 208. A substrate10 can begin on the pedestal 204 and be chucked onto the carrier head70, and/or begin on the carrier head 70 and be dechucked onto thepedestal 204.

Steam is directed through the nozzles 225 to clean and/or preheat one ormore surfaces of the substrate 10 and/or carrier head 70. For example,one or more of the nozzles can be positioned to direct steam onto theouter surface of the carrier head 70, the outer surface 84 a of theretaining ring 84, and/or the bottom surface 84 b of the retaining ring84. One or more of the nozzles can be positioned to direct steam onto afront surface of a substrate 10 being held by the carrier head 70, i.e.,the surface to be polished, or onto the bottom surface of the membrane80 if no substrate 10 is being supported on the carrier head 70. One ormore nozzles can be positioned below the pedestal 204 to direct steamupward onto the front surface of a substrate 10 positioned on pedestal204. One or more nozzles can be positioned above the pedestal 204 todirect steam downward onto a back surface of a substrate 10 positionedon pedestal 204. The carrier head 70 can rotate within the load cup 8and/or move vertically relative to the load cup 8 to allow the nozzles225 to treat different areas of the carrier head 70 and/or substrate 10.The substrate 10 can rest on the pedestal 205 to allow for the interiorsurfaces of the carrier head 70 to be steam treated, e.g., the bottomsurface of the membrane 82, or the inner surfaces of the retaining ring84.

Steam is circulated from a steam source through a supply line 230through the housing 206 to the nozzles 225. The nozzles 225 can spraysteam 245 to remove organic residues, by-product, debris, and slurryparticles left on the carrier head 70 and the substrate 10 after eachpolishing operation. The nozzles 225 can spray steam 245 to heat thesubstrate 10 and/or carrier head 70.

An inter-platen station 9 can be constructed and operated similarly, butneed not have a substrate support pedestal.

The steam 245 delivered by the nozzles 225 can have an adjustabletemperature, pressure, and flow rate to vary the cleaning and preheatingof the carrier head 70 and the substrate 10. In some implementations,the temperature, pressure and/or flow rate can be independentlyadjustable for each nozzle or between groups of nozzles.

For example, the temperature of the steam 245 can be 90 to 200° C. whenthe steam 245 is generated (e.g., in the steam generator 410). Thetemperature of the steam 245 can be between 90 to 150° C. when the steam245 is dispensed by the nozzles 225, e.g., due to heat loss in transit.In some implementations, steam is delivered by the nozzles 225 at atemperature of 70-100° C., e.g., 80-90° C. In some implementations, thesteam delivered by the nozzles is superheated, i.e., is at a temperatureabove the boiling point.

The flow rate of the steam 245 can be 1-1000 cc/minute when the steam245 is delivered by the nozzles 225, depending on heater power andpressure. In some implementations, the steam is mixed with other gases,e.g., is mixed with normal atmosphere or with N₂. Alternatively, thefluid delivered by the nozzles 225 is substantially purely water. Insome implementations, the steam 245 delivered by the nozzles 225 ismixed with liquid water, e.g., aerosolized water. For example, liquidwater and steam can be combined at a relative flow ratio (e.g., withflow rates in sccm) 1:1 to 1:10. However, if the amount of liquid wateris low, e.g., less than 5 wt %, e.g., less than 3 wt %, e.g., less than1 wt %, then the steam will have superior heat transfer qualities. Thus,in some implementations the steam is dry steam, i.e., is substantiallyfree of water droplets.

To avoid degrading the membrane with heat, water can be mixed with thesteam 245 to reduce the temperature, e.g., to around 40-50° C. Thetemperature of the steam 245 can be reduced by mixing cooled water intothe steam 245, or mixing water at the same or substantially the sametemperature into the steam 245 (as liquid water transfers less energythan gaseous water).

In some implementations, a temperature sensor 214 can be installed in oradjacent the steam treating assembly 200 to detect the temperature ofthe carrier head 70 and/or the substrate 10. A signal from the sensor214 can be received by a controller 12 to monitor the temperature of thecarrier head 70 and/or the substrate 10. The controller 12 can controldelivery of the steam by the assembly 100 based on the temperaturemeasurement from the temperature sensor 214. For example, the controllercan receive a target temperature value. If the controller 12 detectsthat the temperature measurement exceeds a target value, the controller12 halt the flow of steam. As another example, the controller 12 canreduce the steam delivery flow rate and/or reduce the steam temperature,e.g., to prevent overheating of the components during cleaning and/orpreheating.

In some implementations, the controller 12 includes a timer. In thiscase, the controller 12 can start when delivery of the steam begins, andcan halt delivery of steam upon expiration of the timer. The timer canbe set based on empirical testing to attain a desired temperature of thecarrier head 70 and substrate 10 during cleaning and/or preheating.

FIG. 2B shows a conditioner steam treating assembly 250 that includes ahousing 255. The housing 255 can form of a “cup” to receive theconditioner disk 92 and conditioner head 93. Steam is circulated througha supply line 280 in the housing 255 to one or more nozzles 275. Thenozzles 275 can spray steam 295 to remove polishing by-product, e.g.,debris or slurry particles, left on the conditioner disk 92 and/orconditioner head 93 after each conditioning operation. The nozzles 275can be located in the housing 255, e.g., on a floor, side wall, orceiling of an interior of the housing 255. One or more nozzles can bepositioned to clean the bottom surface of the pad conditioner disk,and/or the bottom surface, side-walls and/or and top surface of theconditioner head 93. The steam 295 can be generated using the steamgenerator 410. A drain 285 can permit excess water, cleaning solution,and cleaning by-product to pass through to prevent accumulation in thehousing 255.

The conditioner head 93 and conditioner disk 92 can be lowered at leastpartially into the housing 255 to be steam treated. When the conditionerdisk 92 is to be returned to operation, the conditioner head 93 andconditioning disk 92 are lifted out of the housing 255 and positioned onthe polishing pad 30 to condition the polishing pad 30. When theconditioning operation is completed, the conditioner head 93 andconditioning disk 92 are lifted off the polishing pad and swung back tothe housing cup 255 for the polishing by-product on the conditioner head93 and conditioner disk 92 to be removed. In some implementations, thehousing 255 is vertical actuatable, e.g., is mounted to a vertical driveshaft 260.

The housing 255 is positioned to receive the pad conditioner disk 92 andconditioner head 93. The conditioner disk 92 and conditioner head 93 canrotate within the housing 255, and/or move vertically in the housing255, to allow the nozzles 275 to steam treat the various surfaces of theconditioning disk 92 and conditioner head 93.

The steam 295 delivered by the nozzles 275 can have an adjustabletemperature, pressure, and/or flow rate. In some implementations, thetemperature, pressure and/or flow rate can be independently adjustablefor each nozzle or between groups of nozzles. This permits variation andthus more effective the cleaning of the conditioner disk 92 orconditioner head 93.

For example, the temperature of the steam 295 can be 90 to 200° C. whenthe steam 295 is generated (e.g., in the steam generator 410). Thetemperature of the steam 295 can be between 90 to 150° C. when the steam295 is dispensed by the nozzles 275, e.g., due to heat loss in transit.In some implementations, steam can be delivered by the nozzles 275 at atemperature of 70-100° C., e.g., 80-90° C. In some implementations, thesteam delivered by the nozzles is superheated, i.e., is at a temperatureabove the boiling point.

The flow rate of the steam 2945 can be 1-1000 cc/minute when the steam295 is delivered by the nozzles 275. In some implementations, the steamis mixed with other gases, e.g., is mixed with normal atmosphere or withN₂. Alternatively, the fluid delivered by the nozzles 275 issubstantially purely water. In some implementations, the steam 295delivered by the nozzles 275 is mixed with liquid water, e.g.,aerosolized water. For example, liquid water and steam can be combinedat a relative flow ratio (e.g., with flow rates in sccm) 1:1 to 1:10.However, if the amount of liquid water is low, e.g., less than 5 wt %,e.g., less than 3 wt %, e.g., less than 1 wt %, then the steam will havesuperior heat transfer qualities. Thus, in some implementations thesteam is dry steam, i.e., does not include water droplets.

In some implementations, a temperature sensor 264 can be installed in oradjacent the housing 255 to detect the temperature of the conditionerhead 93 and/or conditioner disk 92. The controller 12 can receive asignal from the temperature sensor 264 to monitor the temperature of theconditioner head 93 or conditioner disk 92, e.g., to detect thetemperature of the pad conditioner disk 92. The controller 12 cancontrol delivery of the steam by the assembly 250 based on thetemperature measurement from the temperature sensor 264. For example,the controller can receive a target temperature value. If the controller12 detects that the temperature measurement exceeds a target value, thecontroller 12 halt the flow of steam. As another example, the controller12 can reduce the steam delivery flow rate and/or reduce the steamtemperature, e.g., to prevent overheating of the components duringcleaning and/or preheating.

In some implementations, the controller 12 uses a timer. In this case,the controller 12 can start the time when delivery of steam begins, andhalt delivery of steam upon expiration of the timer. The timer can beset based on empirical testing to attain a desired temperature of theconditioner disk 92 during cleaning and/or preheating, e.g., to preventoverheating.

Referring to FIG. 3A, in some implementations, the polishing station 20includes a temperature sensor 64 to monitor a temperature in thepolishing station or a component of/in the polishing station, e.g., thetemperature of the polishing pad 30 and/or slurry 38 on the polishingpad. For example, the temperature sensor 64 could be an infrared (IR)sensor, e.g., an IR camera, positioned above the polishing pad 30 andconfigured to measure the temperature of the polishing pad 30 and/orslurry 38 on the polishing pad. In particular, the temperature sensor 64can be configured to measure the temperature at multiple points alongthe radius of the polishing pad 30 in order to generate a radialtemperature profile. For example, the IR camera can have a field of viewthat spans the radius of the polishing pad 30. In some implementations,the temperature sensor is a contact sensor rather than a non-contactsensor. For example, the temperature sensor 64 can be thermocouple or IRthermometer positioned on or in the platen 24. In addition, thetemperature sensor 64 can be in direct contact with the polishing pad.

In some implementations, multiple temperature sensors could be spaced atdifferent radial positions across the polishing pad 30 in order toprovide the temperature at multiple points along the radius of thepolishing pad 30. This technique could be use in the alternative or inaddition to an IR camera.

Although illustrated in FIG. 3A as positioned to monitor the temperatureof the polishing pad 30 and/or slurry 38 on the pad 30, the temperaturesensor 64 could be positioned inside the carrier head 70 to measure thetemperature of the substrate 10. The temperature sensor 64 can be indirect contact (i.e., a contacting sensor) with the semiconductor waferof the substrate 10. In some implementations, multiple temperaturesensors are included in the polishing station 22, e.g., to measuretemperatures of different components of/in the polishing station.

The polishing system 20 also includes a temperature control system 100to control the temperature of the polishing pad 30 and/or slurry 38 onthe polishing pad. The temperature control system 100 can include acooling system 102 and/or a heating system 104. At least one, and insome implementations both, of the cooling system 102 and heating system104 operate by delivering a temperature-controlled medium, e.g., aliquid, vapor or spray, onto the polishing surface 36 of the polishingpad 30 (or onto a polishing liquid that is already present on thepolishing pad).

For the cooling system 102, the cooling medium can be a gas, e.g., air,or a liquid, e.g., water. The medium can be at room temperature orchilled below room temperature, e.g., at 5-15° C. In someimplementations, the cooling system 102 uses a spray of air and liquid,e.g., an aerosolized spray of liquid, e.g., water. In particular, thecooling system can have nozzles that generate an aerosolized spray ofwater that is chilled below room temperature. In some implementations,solid material can be mixed with the gas and/or liquid. The solidmaterial can be a chilled material, e.g., ice, or a material thatabsorbs heat, e.g., by chemical reaction, when dissolved in water.

The cooling medium can be delivered by flowing through one or moreapertures, e.g., holes or slots, optionally formed in nozzles, in acoolant delivery arm. The apertures can be provided by a manifold thatis connected to a coolant source.

As shown in FIGS. 3A and 3B, an example cooling system 102 includes anarm 110 that extends over the platen 24 and polishing pad 30 from anedge of the polishing pad to or at least near (e.g., within 5% of thetotal radius of the polishing pad) the center of polishing pad 30. Thearm 110 can be supported by a base 112, and the base 112 can besupported on the same frame 40 as the platen 24. The base 112 caninclude one or more an actuators, e.g., a linear actuator to raise orlower the arm 110, and/or a rotational actuator to swing the arm 110laterally over the platen 24. The arm 110 is positioned to avoidcolliding with other hardware components such as the polishing head 70,pad conditioning disk 92, and the slurry dispensing arm 39.

The example cooling system 102 includes multiple nozzles 120 suspendedfrom the arm 110. Each nozzle 120 is configured to spray a liquidcoolant medium, e.g., water, onto the polishing pad 30. The arm 110 canbe supported by a base 112 so that the nozzles 120 are separated fromthe polishing pad 30 by a gap 126.

Each nozzle 120 can be configured to direct aerosolized water in a spray122 toward the polishing pad 30. The cooling system 102 can include asource 130 of liquid coolant medium and a gas source 132 (see FIG. 3B).Liquid from the source 130 and gas from the source 132 can be mixed in amixing chamber 134 (see FIG. 3A), e.g., in or on the arm 110, beforebeing directed through the nozzle 120 to form the spray 122.

In some implementations, a process parameter, e.g., flow rate, pressure,temperature, and/or mixing ratio of liquid to gas, can be independentlycontrolled for each nozzle. For example, the coolant for each nozzle 120can flow through an independently controllable chiller to independentlycontrol the temperature of the spray. As another example, a separatepair of pumps, one for the gas and one for the liquid, can be connectedto each nozzle such that the flow rate, pressure and mixing ratio of thegas and liquid can be independently controlled for each nozzle.

The various nozzles can spray onto different radial zones 124 on thepolishing pad 30. Adjacent radial zones 124 can overlap. In someimplementations, the nozzles 120 generate a spray impinges the polishingpad 30 along an elongated region 128. For example, the nozzle can beconfigured to generate a spray in a generally planar triangular volume.

One or more of the elongated region 128, e.g., all of the elongatedregions 128, can have a longitudinal axis parallel to the radius thatextends through the region 128 (see region 128 a). Alternatively, thenozzles 120 generate a conical spray.

Although FIG. 1 illustrates the spray itself overlapping, the nozzles120 can be oriented so that the elongated regions do not overlap. Forexample, at least some nozzles 120, e.g., all of the nozzles 120, can beoriented so that the elongated region 128 is at an oblique anglerelative to the radius that passes through the elongated region (seeregion 128 b).

At least some nozzles 120 can be oriented so that a central axis of thespray (see arrow A) from that nozzle is at an oblique angle relative tothe polishing surface 36. In particular, spray 122 can be directed froma nozzle 120 to have a horizontal component in a direction opposite tothe direction of motion of polishing pad 30 (see arrow A) in the regionof impingement caused by rotation of the platen 24.

Although FIGS. 3A and 3B illustrate the nozzles 120 as spaced at uniformintervals, this is not required. The nozzles 120 could be distributednon-uniformly either radially, or angularly, or both. For example, thenozzles 120 can clustered more densely along the radial direction towardthe edge of the polishing pad 30. In addition, although FIGS. 3A and 3Billustrate nine nozzles, there could be a larger or smaller number ofnozzles, e.g., three to twenty nozzles.

For the heating system 104, the heating medium can be a gas, e.g., steam(e.g., from the steam generator 410) or heated air, or a liquid, e.g.,heated water, or a combination of gas and liquid. The medium is aboveroom temperature, e.g., at 40-120° C., e.g., at 90-110° C. The mediumcan be water, such as substantially pure de-ionized water, or water thatthat includes additives or chemicals. In some implementations, theheating system 104 uses a spray of steam. The steam can includesadditives or chemicals.

The heating medium can be delivered by flowing through apertures, e.g.,holes or slots, e.g., provided by one or more nozzles, on a heatingdelivery arm. The apertures can be provided by a manifold that isconnected to a source of the heating medium.

An example heating system 104 includes an arm 140 that extends over theplaten 24 and polishing pad 30 from an edge of the polishing pad to orat least near (e.g., within 5% of the total radius of the polishing pad)the center of polishing pad 30. The arm 140 can be supported by a base142, and the base 142 can be supported on the same frame 40 as theplaten 24. The base 142 can include one or more an actuators, e.g., alinear actuator to raise or lower the arm 140, and/or a rotationalactuator to swing the arm 140 laterally over the platen 24. The arm 140is positioned to avoid colliding with other hardware components such asthe polishing head 70, pad conditioning disk 92, and the slurrydispensing arm 39.

Along the direction of rotation of the platen 24, the arm 140 of theheating system 104 can be positioned between the arm 110 of the coolingsystem 110 and the carrier head 70. Along the direction rotation of theplaten 24, the arm 140 of the heating system 104 can be positionedbetween the arm 110 of the cooling system 110 and the slurry deliveryarm 39. For example, the arm 110 of the cooling system 110, the arm 140of the heating system 104, the slurry delivery arm 39 and the carrierhead 70 can be positioned in that order along the direction rotation ofthe platen 24.

Multiple openings 144 are formed in the bottom surface of the arm 140.Each opening 144 is configured to direct a gas or vapor, e.g., steam,onto the polishing pad 30. The arm 140 can be supported by a base 142 sothat the openings 144 are separated from the polishing pad 30 by a gap.The gap can be 0.5 to 5 mm. In particular, the gap can be selected suchthat the heat of the heating fluid does not significantly dissipatebefore the fluid reaches the polishing pad. For example, the gap can beselected such that steam emitted from the openings does not condensebefore reaching the polishing pad.

The heating system 104 can include a source 148 of steam, e.g., thesteam generator 410, which can be connected to the arm 140 by tubing.Each opening 144 can be configured to direct steam toward the polishingpad 30.

In some implementations, a process parameter, e.g., flow rate, pressure,temperature, and/or mixing ratio of liquid to gas, can be independentlycontrolled for each nozzle. For example, the fluid for each opening 144can flow through an independently controllable heater to independentlycontrol the temperature of the heating fluid, e.g., the temperature ofthe steam.

The various openings 144 can direct steam onto different radial zones onthe polishing pad 30. Adjacent radial zones can overlap. Optionally,some of the openings 144 can be oriented so that a central axis of thespray from that opening is at an oblique angle relative to the polishingsurface 36. Steam can be directed from one or more of the openings 144to have a horizontal component in a direction opposite to the directionof motion of polishing pad 30 in the region of impingement as caused byrotation of the platen 24.

Although FIG. 3B illustrates the openings 144 as spaced at evenintervals, this is not required. The nozzles 120 could be distributednon-uniformly either radially, or angularly, or both. For example,openings 144 could be clustered more densely toward the center of thepolishing pad 30. As another example, openings 144 could be clusteredmore densely at a radius corresponding to a radius at which thepolishing liquid 39 is delivered to the polishing pad 30 by the slurrydelivery arm 39. In addition, although FIG. 3B illustrates nineopenings, there could be a larger or smaller number of openings.

The polishing system 20 can also include a high pressure rinse system106. The high pressure rinse system 106 includes a plurality of nozzles154, e.g., three to twenty nozzles that direct a cleaning fluid, e.g.,water, at high intensity onto the polishing pad 30 to wash the pad 30and remove used slurry, polishing debris, etc.

As shown in FIG. 3B, an example rinse system 106 includes an arm 150that extends over the platen 24 and polishing pad 30 from an edge of thepolishing pad to or at least near (e.g., within 5% of the total radiusof the polishing pad) the center of polishing pad 30. The arm 150 can besupported by a base 152, and the base 152 can be supported on the sameframe 40 as the platen 24. The base 152 can include one or more anactuators, e.g., a linear actuator to raise or lower the arm 150, and/ora rotational actuator to swing the arm 150 laterally over the platen 24.The arm 150 is positioned to avoid colliding with other hardwarecomponents such as the polishing head 70, pad conditioning disk 92, andthe slurry dispensing arm 39.

Along the direction of rotation of the platen 24, the arm 150 of therinse system 106 can be between the arm 110 of the cooling system 110and the arm 140 of the heating system 140. For example, the arm 110 ofthe cooling system 110, the arm 150 of the rinse system 106, the arm 140of the heating system 104, the slurry delivery arm 39 and the carrierhead 70 can be positioned in that order along the direction rotation ofthe platen 24. Alternatively, along the direction of rotation of theplaten 24, the arm 140 of the cooling system 104 can be between the arm150 of the rinse system 106 and the arm 140 of the heating system 140.For example, the arm 150 of the rinse system 106, the arm 110 of thecooling system 110, the arm 140 of the heating system 104, the slurrydelivery arm 39 and the carrier head 70 can be positioned in that orderalong the direction rotation of the platen 24.

Although FIG. 3B illustrate the nozzles 154 as spaced at even intervals,this is not required. In addition, although FIGS. 3A and 3B illustratenine nozzles, there could be a larger or smaller number of nozzles,e.g., three to twenty nozzles.

The polishing system 2 can also include the controller 12 to controloperation of various components, e.g., the temperature control system100. The controller 12 is configured to receive the temperaturemeasurements from the temperature sensor 64 for each radial zone of thepolishing pad. The controller 12 can compare the measured temperatureprofile to a desired temperature profile, and generate a feedback signalto a control mechanism (e.g., actuator, power source, pump, valve, etc.)for each nozzle or opening. The feedback signal is calculated by thecontroller 12 e.g., based on an internal feedback algorithm, to causethe control mechanism to adjust the amount of cooling or heating suchthat the polishing pad and/or slurry reaches (or at least moves closerto) the desired temperature profile.

In some implementations, the polishing system 20 includes a wiper bladeor body 170 to evenly distribute the polishing liquid 38 across thepolishing pad 30. Along the direction of rotation of the platen 24, thewiper blade 170 can be between the slurry delivery arm 39 and thecarrier head 70.

FIG. 3B illustrates separate arms for each subsystem, e.g., the heatingsystem 102, cooling system 104 and rinse system 106, various subsystemscan be included in a single assembly supported by a common arm. Forexample, an assembly can include a cooling module, a rinse module, aheating module, a slurry delivery module, and optionally a wiper module.Each module can include a body, e.g., an arcuate body, that can besecured to a common mounting plate, and the common mounting plate can besecured at the end of an arm so that the assembly is positioned over thepolishing pad 30. Various fluid delivery components, e.g., tubing,passages, etc., can extend inside each body. In some implementations,the modules are separately detachable from the mounting plate. Eachmodule can have similar components to carry out the functions of the armof the associated system described above.

Referring to FIGS. 1, 2A, 2B, 3A and 3B, the controller 12 can monitorthe temperature measurements received by the sensors 64, 214, and 264and control the temperature control system 100 and amount of steamdelivered to the steam treating assembly 200 and 250. The controller 12can continuously monitor the temperature measurements and control thetemperature in a feedback loop, to tune the temperature of the polishingpad 30, the carrier head 70, and the conditioning disk 92. For example,the controller 12 can receive the temperature of the polishing pad 30from the sensor 64, and control the delivery of steam onto the carrierhead 70 and/or conditioner head 92 to raise the temperatures of thecarrier head 70 and/or the conditioner head 92 to match the temperatureof the polishing pad 30. Reducing the temperature difference can helpprevent the carrier head 70 and/or the conditioner head 92 from actingas heat sinks on a relatively higher temperature polishing pad 30, andcan improve within-wafer uniformity.

In some embodiments, the controller 12 stores a desired temperature forthe polishing pad 30, the carrier head 70, and the conditioner disk 92.The controller 12 can monitor the temperature measurements from thesensors 64, 214, and 264 and control the temperature control system 100and the steam treating assembly 200 and/or 250 to bring the temperaturesof the polishing pad 30, the carrier head 70, and/or the conditionerdisk 92 to the desired temperature. By causing the temperatures toachieve a desired temperature, the controller 12 can improvewithin-wafer uniformity and wafer-to-wafer uniformity.

Alternatively, the controller 12 can raise the temperatures of thecarrier head 70 and/or the conditioner head 92 to slightly above thetemperature of the polishing pad 30, to allow for the carrier head 70and/or the conditioner head 92 to cool to the same or substantially thesame temperature of the polishing pad 30 as they move from theirrespective cleaning and pre-heating stations to the polishing pad 30.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

What is claimed is:
 1. An apparatus for steam treatment of a carrierhead or a substrate in a chemical mechanical polishing system,comprising: a load cup; a pedestal in a cavity defined by the load cup,the pedestal configured to receive a substrate from or supply asubstrate to a carrier head; a boiler to generate steam; one or morenozzles positioned to direct steam inwardly into the cavity defined bythe load cup; and a supply line running from the boiler to the one ormore nozzles to supply steam to the one or more nozzles.
 2. Theapparatus of claim 1, comprising a motor to rotate the carrier head whenthe carrier head is within the load cup.
 3. The apparatus of claim 1,comprising an actuator to lift or lower the carrier head within the loadcup.
 4. The apparatus of claim 1, comprising a temperature sensor tomonitor a temperature of the carrier head and/or substrate.
 5. Theapparatus of claim 4, comprising a controller configured to receive thetemperature from the sensor and to halt a flow of steam when the carrierhead or substrate reaches a target temperature.
 6. The apparatus ofclaim 1, further comprising a controller configured to start a timerwhen the steam begins to flow onto the carrier head or substrate and tohalt the flow of steam when the timer expires.
 7. The apparatus of claim1, wherein the one or more nozzles include a first nozzle, and furthercomprising a controller configured to cause steam to flow through thefirst nozzle onto an outer surface of the carrier head when the carrierhead is positioned in the load cup.
 8. The apparatus of claim 1, whereinthe one or more nozzles include a second nozzle, and further comprisinga controller configured to cause steam to flow through the second nozzleonto an interior surface of the carrier head when the substrate ispositioned on the pedestal.
 9. The apparatus of claim 8, wherein thecontroller is configured to cause steam to flow through the secondnozzle onto a bottom surface of the substrate when the substrate isloaded in the carrier head.
 10. The apparatus of claim 1, wherein theone or more nozzles comprise a third nozzle, and further comprising acontroller configured to cause steam to flow through the third nozzleonto a top surface of the substrate when the substrate is positioned onthe pedestal.
 11. The apparatus of claim 10, wherein the one or morenozzles include a fourth nozzle, and wherein the controller isconfigured to cause steam to flow through the fourth nozzle onto abottom surface of the substrate when the substrate is positioned on thepedestal.
 12. A method of steam treatment of a carrier head or asubstrate in a chemical mechanical polishing system, comprising:receiving a carrier head or/or substrate in a substrate loading cup ofthe a chemical mechanical polishing system; and directing steam onto thecarrier head and/or substrate in the loading cup to clean and/or preheatthe carrier head and/or substrate.
 13. An apparatus for steam treatmentof a conditioner head and/or conditioner disk in a chemical mechanicalpolishing system, comprising: a conditioner cleaning cup; a boiler togenerate steam; one or more nozzles positioned to direct steam inwardlyinto a cavity defined by the load cup; and a supply line running fromthe boiler to the one or more nozzles to supply steam to the one or morenozzles.
 14. The apparatus of claim 13, comprising a temperature sensorto monitor a temperature of the conditioner head and/or conditionerdisk.
 15. The apparatus of claim 14, comprising a controller configuredto receive the temperature from the sensor and to halt a flow of steamto the conditioner head or conditioner disk when the conditioner head orconditioner disk reaches a target temperature.
 16. The apparatus ofclaim 13, further comprising a controller configured to start a timerwhen the steam begins to flow onto conditioner head or conditioner diskand to halt the flow of steam when the timer expires.
 17. The apparatusof claim 13, wherein the one or more nozzles include a first nozzle, andfurther comprising a controller is configured to cause steam to flowthrough the first nozzle onto a bottom surface of the conditioner diskwhen the conditioner head is positioned in the cleaning cup.
 18. Theapparatus of claim 13, wherein the one or more nozzles include a secondnozzle, and further comprising a controller configured to cause steam toflow through the second nozzle onto an outer surface of the conditionerhead when the conditioner head is positioned in the cleaning cup.
 19. Amethod of steam treatment of a conditioner head and/or conditioner diskin a chemical mechanical polishing system, comprising: receiving aconditioner head in a conditioner cleaning cup of the a chemicalmechanical polishing system; and directing steam onto the conditionerhead and/or conditioner head in the cleaning cup to clean and/or preheatthe conditioner head and/or conditioner disk.